The popularity of roller skating has increased significantly with the advent of new synthetic materials to replace the old wood, metal, or hard rubber skate rollers. The new materials have enabled use of roller skates, not only in the skate rinks, but also on ordinary paved surfaces. Overall skate design, however, has not changed. The most popular skates still make use of four rollers per skate; two rollers under the toes and two under the heel.
Conventional roller skates are heavy and cumbersome, especially in the toe area, due to the roller weight and supporting truck structure. The usual distribution of weight on the foot is difficult to adjust to and can cause fatigue. Furthermore, the wide stance of the two front rollers forces the skater to move unnaturally when propelling forward or rearwardly. An effort is typically made to keep all four rollers of both skates on the floor or pavement at all times, thereby maximizing control and balance. However, the skate and roller configuration is such that the feet and legs must be contorted into uncomfortable positions when moving, especially over uneven terrain.
Excessive toe weight added by the foot rollers tends to tip the skates forwardly, so the toe rollers are first to touch ground as the skater steps forwardly after "pushing off". This seldom causes problems in roller rinks but can be potentially dangerous in rougher terrain where the front rollers might catch on some obstacle and trip the skater. It is more desirable to lower the rear rollers to the pavement first. Then, if an object is encountered, the front rollers are available to add stability while the rear rollers move over the obstacle. The difficulty is in holding the toes high to let the rear rollers touch first. The muscles used to hold the toes high become easily fatigued and often develop into relatively serious and painful "shin splints".
Design of four wheel roller skates has conventionally been ignored insofar as human anatomy is concerned. Human body weight is not evenly distributed between the heel and toe. Much more weight is borne by the heels than the toes. Also, the overall body weight is centered between the feet rather than centered over each foot. Four wheel roller skates use truck mounts for the rollers that, due to bulk of the trucks, tend to shorten the skate wheel base. The further forward the rear wheels, the more tendency there is for the wheels to shift forwardly suddenly, causing a fall. The same is true of rearward location behind the ball of the foot of the forward rollers.
The laterally centered weight of a skater naturally causes more weight to be borne at the inside of the foot than the outside. Four wheel roller skate trucks are designed to track straight under direct vertical loading. Thus, there is a natural tendency for the skates to "stee" themselves inwardly when the skater's weight is naturally applied to the rollers and trucks. The skater therefore accommodates for this by shifting more weight to the outside surfaces of the feet.
In short, it has continually been the skater making adjustments to accommodate the skate roller placement and geometry of the skates, rather than the skate roller geometry accommodating the skater. This causes safety as well as muscle strain problems, especially when skates are used outdoors over rough terrain and over long periods of time.
These problems have been recognized to a limited extent by previous developers of three wheel roller skates. For example, the 1963 U.S. Patent to Wyche (3,086,787) discloses a three wheel roller skate having a single front roller and dual rear rollers as an answer to part of the difficulties experienced with four roller skates. However, the patent deals primarily with a rigid roller support framework, rather than attending to the several drawbacks remaining even through provision of a single, rather than double, front roller. For example, positioning of the front roller appears to be somewhat behind the "ball" of the toes. The heel, on the other hand, is situated forwardly of the skater's heel. This causes a relatively short wheel base that decreases stability, especially in rough terrain. Furthermore, the rotational axes of the front and rear rollers appear to be parallel. Thus, the Wyche skates will track forwardly or rearwardly only under vertical loading.
Another three wheel roller skate is disclosed by Sessa in U.S. Pat. No. 3,891,225. Sessa, however, was concerned with simulating a snow ski. The "wheel base" between forward and rearward rollers is not confined within the limits of the skater's foot length. Instead, the rollers of the Sessa device are situated in front of and behind the footrest or support. This severely limits the maneuverability of the skater but, nontheless, points further to the advantages of a three roller skate. A similar skate is shown in U.S. Pat. No. 1,854,188 to Gregory.
Another three roller skate is shown by U.S. Pat. No. 1,276,212 to Hardy. Hardy, like Wyche, was concerned primarily with frame rigidity but did recognize the advantages of utilizing three skate rollers for additional stability. The same difficulties remain, however, of improving the safety and comfort of the skate design for use over various terrain.
A substantial need, therefore, remains for roller skates that may use the advantages of the newly developed synthetic rollers, while minimizing the safety risks previously associated with four wheel roller skates, especially in uneven terrain conditions and, further, which will add to the comfort of the skater during long skating sessions.